I have a very simple set-up. Generator sits on a rear deck, with a heavy appliance cord running to a cabinet just behind the driver's seat and under the floor. I also have a short extension cord going from there, up thru the floor, into my inverter cabinet, inside. Outside, I can plug that short ext cord into either the generator's cord, or shore power cord. Inside the inverter cabinet, I have the choice of plugging in to either that short ext cord (for shore/gen power), or the inverter. I wired the bus with regular 14/2 romex, to various receptacles.
For lighting, I used 15w "under cabinet" florescents, in the overheads, under the sink, above the sink, above the dinette, etc., and they are all simply plugged into their own receptacle. My sink pump is wired to a 120v-12v wallwort, which is also plugged into it's own (switched) receptacle.
Any constant 12v draw is wired direct to the battery bank. This way, I can leave the inverter off when not in the camper, or when sleeping. And I always follow the 3 P's, before leaving or going to sleep... power, pump, pressure... I turn off the inverter, turn off power to the pump (just in case I need to leave the inverter on for some reason), and I release any water pressure from the system (again... just in case!).
